A current-carrying connector configured such that the electrodes are not brought into contact with water by being protected with waterproof seals has been disclosed as a prior art (Patent literature 1). However, this technique is not intended for pressure-proof usage, and the electrodes are in an opened state. Accordingly, when one piece of the connector is mated with the other piece in a conductive liquid, if the conductive liquid is adhered to the circumference of the connector, the connector may cause an electrical leakage. When one piece of the connector is mated with the other piece in a flammable gas, the electrodes are in contact with the flammable gas. In such a case, if sparks are generated due to electric discharge, an ignition may occur.
Refer to Patent literature 2 as a document that describes a technique related to the invention to be disclosed in this specification.